Systems and methods for improved performance in semiconductor processing

ABSTRACT

Exemplary etching methods may include flowing a hydrogen-containing precursor into a semiconductor processing chamber. The methods may include flowing a fluorine-containing precursor into a remote plasma region of the semiconductor processing chamber. The methods may include forming a plasma of the fluorine-containing precursor in the remote plasma region. The methods may include etching a pre-determined amount of a silicon-containing material from a substrate in a processing region of the semiconductor processing chamber. The methods may include measuring a radical density within the remote plasma region during the etching. The methods may also include halting the flow of the hydrogen-containing precursor into the semiconductor processing chamber when the radical density measured over time correlates to a produced amount of etchant to remove the pre-determined amount of the silicon-containing material.

TECHNICAL FIELD

The present technology relates to semiconductor processes and equipment.More specifically, the present technology relates to repeatableperformance of plasma etch processing.

BACKGROUND

Integrated circuits are made possible by processes which produceintricately patterned material layers on substrate surfaces. Producingpatterned material on a substrate requires controlled methods forremoval of exposed material. Chemical etching is used for a variety ofpurposes including transferring a pattern in photoresist into underlyinglayers, thinning layers, or thinning lateral dimensions of featuresalready present on the surface. Often it is desirable to have an etchprocess that etches one material faster than another facilitating, forexample, a pattern transfer process. Such an etch process is said to beselective to the first material. As a result of the diversity ofmaterials, circuits, and processes, etch processes have been developedwith a selectivity towards a variety of materials.

Etch processes may be termed wet or dry based on the materials used inthe process. A wet HF etch preferentially removes silicon oxide overother dielectrics and materials. However, wet processes may havedifficulty penetrating some constrained trenches and also may sometimesdeform the remaining material. Dry etches produced in local plasmasformed within the substrate processing region can penetrate moreconstrained trenches and exhibit less deformation of delicate remainingstructures. However, local plasmas may damage the substrate through theproduction of electric arcs as they discharge.

Thus, there is a need for improved systems and methods that can be usedto produce high quality devices and structures. These and other needsare addressed by the present technology.

SUMMARY

Exemplary etching methods may include flowing a hydrogen-containingprecursor into a semiconductor processing chamber. The methods mayinclude flowing a fluorine-containing precursor into a remote plasmaregion of the semiconductor processing chamber. The methods may includeforming a plasma of the fluorine-containing precursor in the remoteplasma region. The methods may include etching a pre-determined amountof a silicon-containing material from a substrate in a processing regionof the semiconductor processing chamber. The methods may includemeasuring a radical density within the remote plasma region during theetching. The methods may also include halting the formation of plasma orflow of the hydrogen-containing precursor into the semiconductorprocessing chamber when the radical density measured over timecorrelates to a produced amount of etchant to remove the pre-determinedamount of the silicon-containing material.

In some embodiments, the measuring may be of an atomic trace of hydrogenwithin the remote plasma region of the semiconductor processing chamber.The hydrogen-containing precursor may be or include hydrogen, ammonia,or water. The measuring may be performed with an optical emissionspectrometer positioned within a dielectric component at least partiallydefining the remote plasma region of the semiconductor processingchamber. The measuring may include measuring a peak intensity of radicalhydrogen within the remote plasma region of the semiconductor processingchamber. The method may also include, prior to halting the flow of thehydrogen-containing precursor, identifying an increase in the atomictrace within the remote plasma region. The increase may correlate tocomplete removal of the silicon-containing material. The remote plasmaregion may be a region defined within the semiconductor processingchamber and separated from the processing region by one or more chambercomponents. The methods may also include flowing an inert precursor intothe remote plasma region and forming a plasma of the inert precursorwithin the remote plasma region. A stable plasma of the inert precursormay be produced prior to flowing the fluorine-containing precursor intothe remote plasma region. The hydrogen-containing precursor may beflowed to bypass the remote plasma region during the etching method.

Some embodiments of the present technology may also encompass chambercleaning methods. The methods may include forming a plasma of afluorine-containing precursor in a semiconductor processing chamber inwhich an etch process utilizing a hydrogen-containing precursor has beenperformed. The methods may include measuring a radical density of thehydrogen-containing precursor. The methods may include extinguishing theplasma of the fluorine-containing precursor when the radical density ofthe hydrogen-containing precursor reaches a pre-determined threshold.

In some embodiments, additional hydrogen-containing precursor may not beflowed into the semiconductor processing chamber during the chambercleaning method. The hydrogen-containing precursor may include hydrogen,ammonia, or anhydrous hydrogen fluoride. The measuring may be of anatomic trace of hydrogen within a remote plasma region of thesemiconductor processing chamber. The methods may include subsequentlyrepeating the etch process utilizing the hydrogen-containing precursor.The etch process as repeated may produce a resultant etch within 5% ofthe etch process initially performed.

Some embodiments of the present technology may also encompass etchingmethods. The methods may include flowing a hydrogen-containing precursorinto a semiconductor processing chamber. The methods may include flowinga fluorine-containing precursor into a remote plasma region of thesemiconductor processing chamber. The methods may include forming aplasma of the fluorine-containing precursor in the remote plasma region.The methods may include etching in a first etch process a pre-determinedamount of a silicon-containing material from a substrate in a processingregion of the semiconductor processing chamber. The methods may includemeasuring a radical density within the remote plasma region during theetching. The methods may include halting the flow of thehydrogen-containing precursor into the semiconductor processing chamberwhen the radical density measured over time correlates to a producedamount of etchant to remove the pre-determined amount of thesilicon-containing material.

The methods may include removing the substrate from the semiconductorprocessing chamber. The methods may include forming a plasma of afluorine-containing precursor in the semiconductor processing chamber.The methods may include measuring a radical density of thehydrogen-containing precursor. The methods may include extinguishing theplasma of the fluorine-containing precursor when the radical density ofthe hydrogen-containing precursor reaches a pre-determined threshold.The methods may also include performing a second etch process. In someembodiments the first etch process and the second etch process may bedifferent etch processes. The first etch process may include a firstetch for a dual damascene etch process, and the second etch process mayinclude a second etch for a dual damascene etch process.

Such technology may provide numerous benefits over conventional systemsand techniques. For example, the processes may provide precise controlon etch processes based on specific amounts of etchant materials formed.Additionally, the processes may allow repeatable etching to be performeddue to consistent chamber cleans based on end points associated withspecific chamber conditions and not arbitrary time considerations. Theseand other embodiments, along with many of their advantages and features,are described in more detail in conjunction with the below descriptionand attached figures.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the disclosedtechnology may be realized by reference to the remaining portions of thespecification and the drawings.

FIG. 1 shows a top plan view of one embodiment of an exemplaryprocessing system according to some embodiments of the presenttechnology.

FIG. 2A shows a schematic cross-sectional view of an exemplaryprocessing chamber according to some embodiments of the presenttechnology.

FIG. 2B shows a detailed view of a portion of the processing chamberillustrated in FIG. 2A according to some embodiments of the presenttechnology.

FIG. 3 shows a bottom plan view of an exemplary showerhead according tosome embodiments of the present technology.

FIG. 4 shows exemplary operations in a method according to someembodiments of the present technology.

FIG. 5 shows exemplary operations in a method according to someembodiments of the present technology.

FIG. 6 shows a graph of peak intensity of various precursors duringprocesses according to some embodiments of the present technology.

FIG. 7 shows a graph of peak intensity of an atomic hydrogen traceaccording to some embodiments of the present technology.

FIG. 8 shows a graph correlating etch rate with radical density over aperiod of time according to some embodiments of the present technology.

FIGS. 9A-9C show cross-sectional views of substrates being processedaccording to some embodiments of the present technology.

FIG. 10 shows an exemplary etching operation transitioning between twomaterials according to some embodiments of the present technology.

Several of the figures are included as schematics. It is to beunderstood that the figures are for illustrative purposes, and are notto be considered of scale unless specifically stated to be of scale.Additionally, as schematics, the figures are provided to aidcomprehension and may not include all aspects or information compared torealistic representations, and may include additional or exaggeratedmaterial for illustrative purposes.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a letter thatdistinguishes among the similar components. If only the first referencelabel is used in the specification, the description is applicable to anyone of the similar components having the same first reference labelirrespective of the letter.

DETAILED DESCRIPTION

As devices produced in semiconductor processing continue to shrink,uniformity, process control, and repeatability are becoming morechallenging from process to process. For example, a chamber may be usedto perform an etch process on multiple wafers, and the processparameters may seek an amount of uniformity between each processperformed, such as a consistent etch amount. Additionally, chambers maybe used to perform multiple etches in sequence, such as performing afirst etch process on a substrate, followed by a second etch process onthe same substrate. Control over the amount being etched can bedifficult when the processes etch different amounts from one another.

For example, when plasma etch processing is performed, precursorbyproducts as well as etchant materials may be absorbed into chambercomponents and maintained within a chamber subsequent a process. Forexample, radical hydrogen may be produced in an etch process, andeffluents may be absorbed within chamber components, which may affectthe amount of material etched, as well as uniformity of etching processto process. The amount of this radical hydrogen and other radicals ormaterials may not be consistent process to process, and thus maintaininga uniform chamber environment may be difficult.

In an attempt to produce a baseline environment within the chamberbefore each etch process, chamber seasoning may be performed before aninitial process, and a chamber clean may be performed subsequent eachprocess. Conventional technologies have performed chamber cleans for aperiod of time, and often assumed that the chamber was generally similarto a baseline. However, depending on the processes performed, chambercleans for a specific amount of time often do not produce a consistentchamber environment for subsequent etches, especially when etchprocesses performed change from one to the next as will be describedwith examples below. The present technology overcomes many of theseissues by monitoring radical density or an atomic trace duringprocessing as well as during cleaning to provide consistent etching aswell as a consistent end point in cleaning regardless of the processperformed.

Although the remaining disclosure will routinely identify specificetching processes utilizing the disclosed technology, it will be readilyunderstood that the systems and methods are equally applicable todeposition and cleaning processes as may occur in the describedchambers, as well as other etching technology that may be performed witha variety of exposed materials that may be maintained or substantiallymaintained. Accordingly, the technology should not be considered to beso limited as for use with the exemplary etching processes or chambersalone. Moreover, although an exemplary chamber is described to providefoundation for the present technology, it is to be understood that thepresent technology can be applied to virtually any semiconductorprocessing chamber that may allow the operations described.

FIG. 1 shows a top plan view of one embodiment of a processing system100 of deposition, etching, baking, and curing chambers according toembodiments. In the figure, a pair of front opening unified pods (FOUPs)102 supply substrates of a variety of sizes that are received by roboticarms 104 and placed into a low pressure holding area 106 before beingplaced into one of the substrate processing chambers 108 a-f, positionedin tandem sections 109 a-c. A second robotic arm 110 may be used totransport the substrate wafers from the holding area 106 to thesubstrate processing chambers 108 a-f and back. Each substrateprocessing chamber 108 a-f, can be outfitted to perform a number ofsubstrate processing operations including the dry etch processesdescribed herein in addition to cyclical layer deposition (CLD), atomiclayer deposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), etch, pre-clean, degas, orientation, and othersubstrate processes.

The substrate processing chambers 108 a-f may include one or more systemcomponents for depositing, annealing, curing and/or etching a dielectricfilm on the substrate wafer. In one configuration, two pairs of theprocessing chambers, e.g., 108 c-d and 108 e-f, may be used to depositdielectric material on the substrate, and the third pair of processingchambers, e.g., 108 a-b, may be used to etch the deposited dielectric.In another configuration, all three pairs of chambers, e.g., 108 a-f,may be configured to etch a dielectric film on the substrate. Any one ormore of the processes described may be carried out in chamber(s)separated from the fabrication system shown in different embodiments. Itwill be appreciated that additional configurations of deposition,etching, annealing, and curing chambers for dielectric films arecontemplated by system 100.

FIG. 2A shows a cross-sectional view of an exemplary process chambersystem 200 with partitioned plasma generation regions within theprocessing chamber. During film etching, e.g., titanium nitride,tantalum nitride, tungsten, silicon, polysilicon, silicon oxide, siliconnitride, silicon oxynitride, silicon oxycarbide, etc., a process gas maybe flowed into the first plasma region 215 through a gas inlet assembly205. A remote plasma system (RPS) 201 may optionally be included in thesystem, and may process a first gas which then travels through gas inletassembly 205. The inlet assembly 205 may include two or more distinctgas supply channels where the second channel (not shown) may bypass theRPS 201, if included.

A cooling plate 203, faceplate 217, ion suppressor 223, showerhead 225,and a substrate support 265, having a substrate 255 disposed thereon,are shown and may each be included according to embodiments. Thepedestal 265 may have a heat exchange channel through which a heatexchange fluid flows to control the temperature of the substrate, whichmay be operated to heat and/or cool the substrate or wafer duringprocessing operations. The wafer support platter of the pedestal 265,which may comprise aluminum, ceramic, or a combination thereof, may alsobe resistively heated in order to achieve relatively high temperatures,such as from up to or about 100° C. to above or about 1100° C., using anembedded resistive heater element.

The faceplate 217 may be pyramidal, conical, or of another similarstructure with a narrow top portion expanding to a wide bottom portion.The faceplate 217 may additionally be flat as shown and include aplurality of through-channels used to distribute process gases. Plasmagenerating gases and/or plasma excited species, depending on use of theRPS 201, may pass through a plurality of holes, shown in FIG. 2B, infaceplate 217 for a more uniform delivery into the first plasma region215.

Exemplary configurations may include having the gas inlet assembly 205open into a gas supply region 258 partitioned from the first plasmaregion 215 by faceplate 217 so that the gases/species flow through theholes in the faceplate 217 into the first plasma region 215.

Structural and operational features may be selected to preventsignificant backflow of plasma from the first plasma region 215 backinto the supply region 258, gas inlet assembly 205, and fluid supplysystem 210. The faceplate 217, or a conductive top portion of thechamber, and showerhead 225 are shown with an insulating ring 220located between the features, which allows an AC potential to be appliedto the faceplate 217 relative to showerhead 225 and/or ion suppressor223. The insulating ring 220 may be positioned between the faceplate 217and the showerhead 225 and/or ion suppressor 223 enabling a capacitivelycoupled plasma (CCP) to be formed in the first plasma region. A baffle(not shown) may additionally be located in the first plasma region 215,or otherwise coupled with gas inlet assembly 205, to affect the flow offluid into the region through gas inlet assembly 205.

In some embodiments, insulating ring 220 may be a ceramic or otherdielectric material, and may include a port through which a sensor 222may be positioned. Insulating ring 220 may define a height of the remoteplasma region, or otherwise contribute to defining the region. Sensor222 may be part of an optical emission spectrometer that may be used tomeasure radical density within plasma region 215 as will be explained indetail further below.

The ion suppressor 223 may comprise a plate or other geometry thatdefines a plurality of apertures throughout the structure that areconfigured to suppress the migration of ionically-charged species out ofthe first plasma region 215 while allowing uncharged neutral or radicalspecies to pass through the ion suppressor 223 into an activated gasdelivery region between the suppressor and the showerhead. Inembodiments, the ion suppressor 223 may comprise a perforated plate witha variety of aperture configurations. These uncharged species mayinclude highly reactive species that are transported with less reactivecarrier gas through the apertures. As noted above, the migration ofionic species through the holes may be reduced, and in some instancescompletely suppressed. Controlling the amount of ionic species passingthrough the ion suppressor 223 may advantageously provide increasedcontrol over the gas mixture brought into contact with the underlyingwafer substrate, which in turn may increase control of the depositionand/or etch characteristics of the gas mixture. For example, adjustmentsin the ion concentration of the gas mixture can significantly alter itsetch selectivity, e.g., SiNx:SiOx etch ratios, Si:SiOx etch ratios, etc.In alternative embodiments in which deposition is performed, it can alsoshift the balance of conformal-to-flowable style depositions fordielectric materials.

The plurality of apertures in the ion suppressor 223 may be configuredto control the passage of the activated gas, i.e., the ionic, radical,and/or neutral species, through the ion suppressor 223. For example, theaspect ratio of the holes, or the hole diameter to length, and/or thegeometry of the holes may be controlled so that the flow ofionically-charged species in the activated gas passing through the ionsuppressor 223 is reduced. The holes in the ion suppressor 223 mayinclude a tapered portion that faces the plasma excitation region 215,and a cylindrical portion that faces the showerhead 225. The cylindricalportion may be shaped and dimensioned to control the flow of ionicspecies passing to the showerhead 225. An adjustable electrical bias mayalso be applied to the ion suppressor 223 as an additional means tocontrol the flow of ionic species through the suppressor.

The ion suppressor 223 may function to reduce or eliminate the amount ofionically charged species traveling from the plasma generation region tothe substrate. Uncharged neutral and radical species may still passthrough the openings in the ion suppressor to react with the substrate.It should be noted that the complete elimination of ionically chargedspecies in the reaction region surrounding the substrate may not beperformed in embodiments. In certain instances, ionic species areintended to reach the substrate in order to perform the etch and/ordeposition process. In these instances, the ion suppressor may help tocontrol the concentration of ionic species in the reaction region at alevel that assists the process.

Showerhead 225 in combination with ion suppressor 223 may allow a plasmapresent in first plasma region 215 to avoid directly exciting gases insubstrate processing region 233, while still allowing excited species totravel from chamber plasma region 215 into substrate processing region233. In this way, the chamber may be configured to prevent the plasmafrom contacting a substrate 255 being etched. This may advantageouslyprotect a variety of intricate structures and films patterned on thesubstrate, which may be damaged, dislocated, or otherwise warped ifdirectly contacted by a generated plasma. Additionally, when plasma isallowed to contact the substrate or approach the substrate level, therate at which oxide species etch may increase. Accordingly, if anexposed region of material is oxide, this material may be furtherprotected by maintaining the plasma remotely from the substrate.

The processing system may further include a power supply 240electrically coupled with the processing chamber to provide electricpower to the faceplate 217, ion suppressor 223, showerhead 225, and/orpedestal 265 to generate a plasma in the first plasma region 215 orprocessing region 233. The power supply may be configured to deliver anadjustable amount of power to the chamber depending on the processperformed. Such a configuration may allow for a tunable plasma to beused in the processes being performed. Unlike a remote plasma unit,which is often presented with on or off functionality, a tunable plasmamay be configured to deliver a specific amount of power to the plasmaregion 215. This in turn may allow development of particular plasmacharacteristics such that precursors may be dissociated in specific waysto enhance the etching profiles produced by these precursors.

A plasma may be ignited either in chamber plasma region 215 aboveshowerhead 225 or substrate processing region 233 below showerhead 225.Plasma may be present in chamber plasma region 215 to produce theradical precursors from an inflow of, for example, a fluorine-containingprecursor or other precursor. An AC voltage typically in the radiofrequency (RF) range may be applied between the conductive top portionof the processing chamber, such as faceplate 217, and showerhead 225and/or ion suppressor 223 to ignite a plasma in chamber plasma region215 during deposition. An RF power supply may generate a high RFfrequency of 13.56 MHz but may also generate other frequencies alone orin combination with the 13.56 MHz frequency.

FIG. 2B shows a detailed view 253 of the features affecting theprocessing gas distribution through faceplate 217. As shown in FIGS. 2Aand 2B, faceplate 217, cooling plate 203, and gas inlet assembly 205intersect to define a gas supply region 258 into which process gases maybe delivered from gas inlet 205. The gases may fill the gas supplyregion 258 and flow to first plasma region 215 through apertures 259 infaceplate 217. The apertures 259 may be configured to direct flow in asubstantially unidirectional manner such that process gases may flowinto processing region 233, but may be partially or fully prevented frombackflow into the gas supply region 258 after traversing the faceplate217.

The gas distribution assemblies such as showerhead 225 for use in theprocessing chamber section 200 may be referred to as dual channelshowerheads (DCSH) and are additionally detailed in the embodimentsdescribed in FIG. 3. The dual channel showerhead may provide for etchingprocesses that allow for separation of etchants outside of theprocessing region 233 to provide limited interaction with chambercomponents and each other prior to being delivered into the processingregion.

The showerhead 225 may comprise an upper plate 214 and a lower plate216. The plates may be coupled with one another to define a volume 218between the plates. The coupling of the plates may be so as to providefirst fluid channels 219 through the upper and lower plates, and secondfluid channels 221 through the lower plate 216. The formed channels maybe configured to provide fluid access from the volume 218 through thelower plate 216 via second fluid channels 221 alone, and the first fluidchannels 219 may be fluidly isolated from the volume 218 between theplates and the second fluid channels 221. The volume 218 may be fluidlyaccessible through a side of the gas distribution assembly 225.

FIG. 3 is a bottom view of a showerhead 325 for use with a processingchamber according to embodiments. Showerhead 325 may correspond with theshowerhead 225 shown in FIG. 2A. Through-holes 365, which show a view offirst fluid channels 219, may have a plurality of shapes andconfigurations in order to control and affect the flow of precursorsthrough the showerhead 225. Small holes 375, which show a view of secondfluid channels 221, may be distributed substantially evenly over thesurface of the showerhead, even amongst the through-holes 365, and mayhelp to provide more even mixing of the precursors as they exit theshowerhead than other configurations.

The chamber discussed previously may be used in performing exemplarymethods including etching methods. Turning to FIG. 4 is shown exemplaryoperations in a method 400 according to some embodiments of the presenttechnology. Method 400 may relate to an etching method for asilicon-containing material, and it is to be understood that the methodmay include one or more operations prior to the initiation of themethod. These operations may include front end processing, deposition,gate formation, etching, polishing, cleaning, or any other operationsthat may be performed prior to the described operations. The method mayinclude a number of optional operations, which may or may not bespecifically associated with some embodiments of methods according tothe present technology. For example, many of the operations aredescribed in order to provide a broader scope of the structuralformation, but are not critical to the technology, or may be performedby alternative methodology as will be discussed further below.

Method 400 may or may not involve optional operations to develop thesemiconductor structure to a particular fabrication operation. It is tobe understood that method 400 may be performed on any number ofsemiconductor structures, and examples provided are not intended tolimit the scope of the technology. Other exemplary structures mayinclude two-dimensional and three-dimensional structures common insemiconductor manufacturing, and within which a silicon-containingmaterial is to be removed relative to one or more other materials, asthe present technology may selectively remove silicon-containingmaterials, such as polysilicon, silicon oxide, silicon nitride, siliconcarbide, or other silicon-containing materials.

Method 400 may be based on a plasma etch process in which plasmaeffluents are utilized to remove silicon-containing materials. In plasmaprocessing, determining when the etch process has been completed may bedifficult when remote plasma is utilized. For example, in chamber 200described above, plasma effluents may be formed in remote plasma region215. Sensor 222 may be used with an optical emission spectrometer(“OES”), which may allow measurements of constituent materials generatedin the plasma region. However, the etch process itself may occur inregion 233, which may not be visible to measurement equipment in someembodiments. Additionally, due to characteristics such as a positivepressure environment, for example, etch byproducts may be drawn from thesystem, and thus may also not be visible by sensor 222 or otherequipment. The present methodology may utilize measurements within theremote plasma region to determine an amount of etching that may beperformed.

Method 400 may include flowing a hydrogen-containing precursor into aprocessing chamber at operation 405, and may include flowing afluorine-containing precursor into the processing chamber at operation410. The precursors may be flowed in any order, or may be co-flowed intothe chamber. These materials may be utilized in a plasma process, wherea plasma is formed from the fluorine-containing precursor in operation415. The plasma effluents may be used to produce an etchant includingboth hydrogen and fluorine, and which may be formed or flowed into aprocessing region in which a substrate is housed. The etchant may beused to etch silicon-containing materials that reside on the substrateas noted above in operation 420. Sensor 222 may be used to measureradical density in the remote plasma region during the etching atoperation 425, or may be used to measure one or more atomic traceswithin the chamber. Once a pre-determined amount of silicon-containingmaterial has been etched, the flow of the hydrogen-containing precursormay be halted at operation 430, or the process may otherwise be halted,such as by extinguishing the plasma, for example. By measuring certainradical densities, control of the etch process and a determination of anamount of etchant produced may be afforded.

One exemplary etch process may utilize nitrogen trifluoride and hydrogenas the two precursors, although these precursors are intended to beexamples only, and any other fluorine or hydrogen-containing precursorsmay also be used as will be described below. One or both of theprecursors may be flowed into a remote plasma region of a semiconductorprocessing chamber. For example, both precursors may be flowed into theremote plasma region, or only the fluorine-containing precursor may beflowed into the remote plasma region, while the hydrogen-containingprecursor is flowed to bypass the remote plasma region, such as throughshowerhead 225, to interact with the plasma effluents in the processingregion as described above.

The fluorine-containing precursor may be used to producefluorine-containing radical effluents in region 215, which may then flowthrough the chamber components to interact with the hydrogen-containingprecursor in the processing region to produce an etchant for removingsilicon-containing materials. The reaction mechanism producing thehydrogen-and-fluorine containing etchant may also produce additionalhydrogen radical that is not consumed in formation of the etchant. Forexample, with hydrogen gas or other hydrogen-containing precursors, whenfluorine radicals interact with the precursor, the resultant productsmay be a molecule of hydrogen fluoride, and a residual radical hydrogenatom. Despite the positive pressure within the chamber environment, orthe component profiles within the chamber, radical hydrogen may freelybackflow from the processing region into the remote plasma region 215,where it may be measured by sensor 222 for the OES. In some optionalembodiments, in formation of a stable plasma prior to delivery of thefluorine-containing precursor, an inert precursor, such as helium forexample, may be used to strike a plasma in the remote region 215. Once astable plasma has been formed with the inert precursor, delivery of thefluorine-containing precursor may commence.

Regardless of the order of precursor delivery, once thefluorine-containing precursor is delivered, the formation of hydrogenfluoride may produce an amount of radical hydrogen, which may be visibleto the OES, such as with the atomic trace of hydrogen. The amount ofradical hydrogen produced may be used in a correlation to determine anamount of etchant produced, and which may be further used to determinean amount of silicon-containing material that will be removed. Testinghas confirmed the consistency of this correlation, especially whenchamber cleaning according to some embodiments is performed, allowing aradical density of the hydrogen to be used to estimate an amount involume or depth of silicon-containing material that will be removed.

Skipping to FIG. 6 is shown a graph of peak intensity of variousprecursors during processes according to some embodiments of the presenttechnology. In the upper chart, the radical intensity of variousprecursors is shown during etch process 400. As illustrated, peaks 605and 610 correlate to hydrogen radicals residing in the remote plasmaregion. Peak 615 illustrates fluorine concentration, and is minimallyvisible. When precursors such as nitrogen trifluoride are delivered intothe remote plasma region, formed fluorine radicals will almostimmediately combine with radical hydrogen to produce hydrogen fluoride,and thus the fluorine itself may be less visible to the OES asillustrated. Accordingly, although fluorine is a component of theetchant used to etch the silicon-containing material, the monitoring maybe performed on the hydrogen radical of the hydrogen-containingprecursor in method 400, and/or on HF or other hydrogen-containingmaterials in alternative methods. By measuring peak intensity of thehydrogen-containing precursor or hydrogen radical, the etch may becontrolled by correlating the amount of etchant produced as well as theetch rate. As radical density as identified by peak intensity of aparticular atomic trace is increased, etchant amount may be increased,and additional etching may occur and/or increased etch rate may occur.As radical density decreases, etchant amount may decrease and/or etchrate may reduce. This will be described further in a detailed exampleincluding both an etch process according to some embodiments of thepresent technology as well as a cleaning process according to someembodiments of the present technology.

Precursors used in the method may be selected based on thesilicon-containing material to be etched, but may generally include afluorine-containing precursor or a halogen-containing precursor. Anexemplary fluorine-containing precursor may be nitrogen trifluoride(NF₃), which may be flowed into the remote plasma region, which may beseparate from, but fluidly coupled with, the processing region. Othersources of fluorine may be used in conjunction with or as replacementsfor the nitrogen trifluoride. In general, a fluorine-containingprecursor may be flowed into the remote plasma region and thefluorine-containing precursor may include at least one precursorselected from the group of atomic fluorine, diatomic fluorine, nitrogentrifluoride, carbon tetrafluoride, hydrogen fluoride including anhydroushydrogen fluoride, xenon difluoride, and various otherfluorine-containing precursors used or useful in semiconductorprocessing. The precursors may also include any number of carrier gases,which may include nitrogen, helium, argon, or other noble, inert, oruseful precursors.

The hydrogen-containing precursor may include hydrogen, a hydrocarbon,water vapor, an alcohol, such as isopropyl alcohol, hydrogen peroxide,or other materials that may include hydrogen as would be understood bythe skilled artisan. Additional precursors such as carrier gases orinert materials may be included with the hydrogen-containing precursorsas well. In some embodiments, the hydrogen-containing precursor, such ashydrogen gas or ammonia, may be maintained fluidly isolated from aplasma that may be formed within the remote plasma region. Inembodiments, the plasma processing region may be maintained plasma freeduring the removal operations. By plasma free is meant that plasma maynot be actively formed within the processing region during theoperations, although plasma effluents produced remotely as describedearlier, may be used during the operations.

Turning to FIG. 5 is shown exemplary operations in a cleaning method 500according to some embodiments of the present technology. Cleaning method500 may be performed after any number of plasma processes includingetching, deposition, or other processes which may produce residualmaterials within the chamber. For example, despite purging, radicalmaterials produced during a method, such as etching method 400 among anyother method, as well as initial precursors may remain within thechamber. These radical materials may affect subsequent processesperformed. For example, residual hydrogen radicals may afford increasedetchant in a subsequent etch process, which may result in increased etchover a previous etch. By utilizing a similar OES measurement as inmethod 400, control over subsequent etch processes may be improved byensuring a relatively consistent chamber environment process to process.

Because hydrogen radical may be absorbed within chamber components, theamount of hydrogen radical maintained within the chamber may not reachzero, but may plateau over time as it is removed from the system and/ordesorbed from chamber surfaces. Some conventional processes performcleaning operations for a set amount of time, regardless of the processperformed, in an attempt to create a consistent chamber environment.However, because the amount of hydrogen that may be removed from thesystem may not be consistent, once the next etch process is performed,too much residual hydrogen may remain, or the absorption process similarto seasoning may occur, which may affect the amount of etching as wellas the uniformity of etching in subsequent processes. Cleaning methodsaccording to the present technology may resolve these issues byperforming a dynamic clean that seeks to produce a pre-determined levelof hydrogen radical, as opposed to perform a clean for a pre-determinedamount of time.

Method 500 may optionally include removing a substrate on which an etchwas performed in operation 505, such as etch method 400, although insome embodiments the substrate may be maintained within the chamber. Atoperation 510, a fluorine-containing precursor may be flowed into aprocessing chamber, such as into a similar or different remote plasmaregion or elsewhere, and a plasma may be formed of thefluorine-containing precursor. The produced fluorine plasma effluentsmay then perform the same or similar operations as in method 400 withrespect to the interaction with the hydrogen, but may scavenge residualhydrogen material within the processing chamber. In some embodiments,method 500 may not include any additional flow of thehydrogen-containing precursor used in an etch process performed in theprocessing chamber, and in some embodiments method 500 may not includeany hydrogen-containing precursors.

By not flowing any additional hydrogen-containing precursor, theproduced fluorine radicals may combine with any residualhydrogen-containing precursor and be purged from the chamber. Similar tomethod 400, method 500 may include measuring radical density atoperation 515, such as with an optical emission spectrometer or OESdescribed previously that may measure an atomic trace intensity.Although the radical density may be measured anywhere in the chamber, ifalready incorporated within the remote plasma region, the measurementfor method 500 may also be performed in this region, even if thefluorine-containing radical is produced elsewhere, such as upstream inan RPS unit. The OES may be used to measure constituent materials in theenvironment to determine removal of the hydrogen materials. Once thehydrogen material has been sufficiently removed, the amount of fluorineradical may begin to increase within the system.

As noted above, hydrogen may not be completely removed as it may beabsorbed within chamber components. Although this material may begin tobe desorbed from the chamber, the amount of fluorine may build up in thesystem, while the amount of hydrogen continues to reduce. This may bemonitored with the OES, and once a particular radical density has beenachieved, such as when the radical density of the hydrogen-containingprecursor reaches a pre-determined threshold as identified by areduction in atomic trace intensity, or as a measure of relativedepletion or a percentage drop, flow of the fluorine-containingprecursor may be halted, or the plasma of the fluorine-containingprecursor may be extinguished at operation 520. Method 500 may includeany of the precursors and/or carrier gases previously described, and maybe used subsequent any number of process operations to produce asubstantially consistent chamber environment. In some embodiments, asubsequent etch process may be performed at optional operation 525. Thesubsequent etch process may be the previous etch process repeated on asubsequent substrate, or a subsequent etch may be performed on the samesubstrate as will be described below. Embodiments of the presenttechnology may allow improved reproduction of etch and other plasmaprocesses, and in some embodiments, embodiments of the presenttechnology may allow repeated etch processes to be performed within 10%margin of error of the results of a previous etch process, and in someembodiments within 9% margin of error, within 8% margin of error, within7% margin of error, within 6% margin of error, within 5% margin oferror, within 4% margin of error, within 3% margin of error, within 2%margin of error, or may produce substantially or essentially similarresults for repeated etch processes.

Returning to FIG. 6, the bottom chart may illustrate performance of thecleaning method 500 utilizing the same components within a processingchamber as utilized in method 400, such as an OES positioned to measureradical density within the remote plasma region. As illustrated, as thecleaning method is performed, the hydrogen peaks are reduced asillustrated by peaks 620 and 625, which correspond to peaks 605 and 610produced during the etch process.

As the cleaning method is continued, while the hydrogen peaks begin toplateau near a minimum, fluorine concentration may increase, and maybecome more apparent as illustrated by peak 630, which corresponds tothe fluorine peak 615 produced during the etch process. As will beexplained with an example below, the cleaning method may be performed toproduce a residual hydrogen amount that may allow a consistent chamberenvironment for subsequent processes.

The previous figures have illustrated how peak intensity of OESmeasurements may be used to monitor a process being performed. Byisolating and monitoring particular peaks over time, the presenttechnology may afford correlations and processes that produce consistentand controlled etching and cleaning processes. FIG. 7 shows arepresentative graph of peak intensity of hydrogen according to someembodiments of the present technology. The figure may illustrate when aprocess is performed, which may include a combined etching and cleaningoperation. In some embodiments method 400 and method 500 may be combinedto produce an etching method that may include a subsequent cleaning. Thecleaning may refresh the chamber for a subsequent process, such as asecondary etch process, which may be the same or different from thefirst etch process in embodiments.

The chart in FIG. 7 shows a single process being performed according tosome embodiments of the present technology, but it is to be understoodthat the figure is only included to further explain the technology,which may be performed with regard to measurement of other materials bythe OES, and may be used in almost any plasma-processing to monitor theprocess for control on the initial process being performed, as well ascontrol on the cleaning process to produce a consistent environment.

The graph illustrates a single peak for hydrogen atomic trace intensityin a remote plasma region of a semiconductor processing chamber. At theleft of the chart, the peak intensity is low as the process has not yetbegun, although hydrogen may be flowing into the chamber. As explainedabove, the hydrogen-containing precursor may bypass the remote plasmaregion. Additionally, because the OES may be measuring atomic traceintensity, no or minimal hydrogen radical may be present. At position705, a plasma may be ignited as previously described. In someembodiments the plasma may be ignited from a fluorine-containingprecursor, although in other embodiments the plasma may be formed froman inert precursor, such as helium, for example. By initially formingthe plasma from an inert precursor, improved estimates of producedetchant may be afforded.

With the hydrogen-containing and inert precursors flowing, and a plasmaformed in the remote plasma region, hydrogen radical concentrationmeasured as intensity of the atomic H trace may increase beginning atposition 705 within the remote plasma region as the plasma is formed andstabilizes. At position 710, the fluorine-containing precursor may beflowed into the remote plasma region, and fluorine radicals may beproduced. As explained previously, fluorine radicals may produce ahydrogen-and-fluorine-containing etchant, as well as additional hydrogenradical, and thus beginning at position 710, the hydrogen peak intensitymay rise considerably based on the generation of additional hydrogenradical. Based on the flow rates of the precursors, the process mayproduce a consistent amount of etchant, and hence consistent amount ofadditional hydrogen radical, as illustrated by the maintained peakintensity of hydrogen during the etch process. At position 715, the etchprocess may be completed by halting the flow of the hydrogen-containingprecursor and/or stopping the plasma process. The substrate may or maynot be removed from the processing chamber before a cleaning process isperformed.

As previously explained, an inert precursor may be used to strike andstabilize the plasma, as illustrated by the jagged curve producedbetween 705 and 710. From 710 to 715, the fluorine-containing precursoris also flowed into the chamber and plasma, and etchant is produced. Aspreviously explained, a correlation based on the reaction chemistry mayallow measurement of an amount of hydrogen radical or reactive etchantsproduced to be used to determine, such as via calculation, an amount ofetchant produced. To determine an amount of hydrogen radical produced,the area under the peak intensity of hydrogen radical may be integratedbetween position 710 and 715. This may allow a determination of theamount of hydrogen radical produced, which may allow an amount ofetchant produced to be calculated. Depending on the material to beetched, and the reaction chemistry of the etch, by knowing the amount ofetchant produced, the amount of material removed can also be calculated.This can provide improved control on etch processes. For example, in aprocess in which a particular amount of material is to be removed, thecalculations may be reversed to determine how much hydrogen radicalwould be produced. The process may then be performed, and when theintegrated area correlates to the calculated amount of hydrogen radical,the process can be halted with confidence that the desired amount ofetch has been performed. Correction factors may be included with any ofthese calculations to account for materials adsorbed to chambercomponents, or otherwise lost during the process.

In other processes, the etch may be performed until complete removal ofa material occurs, such as removal to an etch stop material. In thesecases, the integration may not be necessary. Once the removal has beencompleted, no further etching may occur, and etchant may begin to buildin the system, along with an increase in hydrogen radical, and the peakintensity of hydrogen radical may begin to drift upward as will be notedbelow. This may be used as an indication that the process has beencompleted, and the process may be halted.

After the process has been stopped at position 715, the substrate may beremoved from the chamber to perform a cleaning process, or the substratemay remain in the processing chamber in other embodiments. Although flowof the hydrogen-containing precursor may have been ceased, somehydrogen-containing precursor may remain within the processing chamber,as previously described. Depending on the etch performed, the amount ofresidual hydrogen may be variable. At position 720, thefluorine-containing precursor may be reintroduced into the processingchamber, and a plasma may be formed to produce radicalfluorine-containing materials. Residual hydrogen-containing precursormay be dissociated producing additional hydrogen radicals asillustrated. No additional hydrogen-containing precursor may be flowedinto the processing chamber, while the fluorine-containing precursor isflowed, and thus as radical fluorine is produced, the produced hydrogenradicals may be consumed and purged from the system, and the amount ofhydrogen radical may steadily decrease as illustrated.

Because of the amount of adsorption, the amount of hydrogen may notreach zero, which may be acceptable to allow a subsequent process to notlose substantial precursors to re-adsorption. Once the hydrogen radicaldensity, as indicated by peak intensity, has reached a predeterminedamount to be produced for each cleaning process, the plasma may beextinguished at position 725, and/or the flow of the fluorine-containingprecursor may be halted. As an alternative, the process may monitor apercentage drop in the H signal, or removal amount. At a predeterminedlevel of drop or when the signal drop may be less than or about 1%,about 2%, about 5%, or some other delta between multiple consecutivedata points, the operation may be terminated. A second etch process maythen be performed on the previous substrate or on a subsequent substrateon which the etch process is to be performed. The amount of cleaningperformed may also affect the curve of hydrogen radical produced, whichmay indicate the amount of etchant produced. For example, when a shortercleaning process is performed, indicative of more residual hydrogen, ahigher etch rate may be performed in subsequent processes, as the curverises in intensity, indicative of increased hydrogen radical density andproduced etchant. As the cleaning process is performed to a lowerresidual hydrogen density, subsequent processes may initially produceless hydrogen radical and etchant, thereby providing lower etch rates.This may afford further control on etch processes performed wheregreater amounts of material are to be removed, or where fine control ofremoval is desired.

As previously discussed, the residual amount of hydrogen radical may bebased on the etch process performed. For example, if additional materialwas to be removed, the process may be performed for a longer period oftime, which may produce a longer area under the curve, or increasedintegrated area. FIG. 8 shows a graph showing the correlation betweenetch amount and the integrated area of the hydrogen signal according tosome embodiments of the present technology. While flow rates may be usedto tune the intensity of the peaks and the etch rate, the time at whichthe peak is formed may correlate to the etch amount. As shown in thechart, as the integrated area under the curve increases, etch amountincreases substantially linearly. Accordingly, the calculationsdiscussed before can be used to produce repeatable results where timeand peak intensity can be used to precisely control etch processes. Byperforming cleaning operations to maintain a consistent chamberenvironment, these processes can be repeated substrate to substrate.

In addition to repeatability of similar processes, some embodiments ofthe present technology may be used to produce controlled multi-partetches. FIGS. 9A-9C show cross-sectional views of substrate 900 beingprocessed according to some embodiments of the present technology. It isto be understood that the example is intended only to illustrate oneapplication of the present technology, which may be used for any numberof other processes including dummy gate removal, fin trimming, capremoval, and many other processes.

As illustrated in FIG. 9A, substrate 900 may include a base 905, whichmay be a wafer or substrate on which additional layers may be formed,and which may be any intermediate layer in a semiconductor structurethrough which connections may be made. Interlayer dielectric layers 915and 920 may be formed over substrate 900, with etch stop layer 910formed to protect substrate 905 from over etch. Although shown as twolayers, layers 915 and 920 may be a single layer of material byutilizing embodiments of the present technology, although in otherembodiments an additional etch stop layer may be formed between thesetwo layers as well. Etch processes utilizing precursors as previouslydescribed may be used, such as discussed with regard to method 400.

FIG. 9B illustrates a first etch that may be facilitated by photoresistformed above the layers. The etch may be performed down to the etch stoplayer 910. Utilizing some embodiments of the present technology, theprocess may be performed until the hydrogen radical peak intensitydrifts as the process reaches the etch stop barrier, indicating theprocess has completed. A chamber clean, such as utilizing method 500,may be performed to refresh the chamber, and then a second etch processmay be performed to etch layer 920 to produce the damascene structure asillustrated in FIG. 9C. Subsequent punch through and metallization maybe performed as would be understood.

In the second etch performed, a controlled removal to a particularheight may be desired, and may be based on a known thickness of layer920, or a known removal thickness required. In this scenario, an amountof etchant to produce this amount of removal may be calculated, and anamount of hydrogen radical produced may be further calculated. Theprocess may be performed while integrating the area under the hydrogenpeak intensity curve, and once the area correlates to the calculatedhydrogen radical density produced and related to the desired etchant,the process may be halted. This may afford a specifically controlledetch to a desired height without the need for additional etch stoplayers in some embodiments. A subsequent clean process may be performed,and the next substrate may be processed with the next multi-part etch.

FIG. 10 illustrates an amount of signal drift for the H-signal as anindication of a completed operation. As illustrated, a removal operationof a first material, such as a silicon-containing material, for example,may be performed, and an emission signal maybe observed from position1010. After the first material has been removed, such as if disposedover a second material, the etchant signal may adjust at position 1020as the second material is exposed to the etchant, and is observedthrough position 1030. This may be utilized as an indication of theprocess being completed, and may provide an additional mechanism forending the process by extinguishing a plasma, or by halting the flow ofone or more etchant materials.

In this and other multi-part etch scenarios, the first etch process andthe second etch process may be performed for different amounts of time,different precursor flow rates, and/or different etch conditions. Thismay produce outcomes where different amounts of residual hydrogen may bepresent within the chamber. Accordingly, the chamber clean performed inbetween etches for a single substrate, and the chamber clean performedbetween substrates, may be performed for different amounts of time, butmay be performed to an end point of a similar residual hydrogenconcentration. By performing these dynamic cleaning operations, alongwith the precise etching processes of the present technology, consistentprocesses and calculations may be performed, which may afford increaseduniformity process to process and substrate to substrate.

In the preceding description, for the purposes of explanation, numerousdetails have been set forth in order to provide an understanding ofvarious embodiments of the present technology. It will be apparent toone skilled in the art, however, that certain embodiments may bepracticed without some of these details, or with additional details.

Having disclosed several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theembodiments. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent technology. Accordingly, the above description should not betaken as limiting the scope of the technology. Additionally, methods orprocesses may be described as sequential or in steps, but it is to beunderstood that the operations may be performed concurrently, or indifferent orders than listed.

Where a range of values is provided, it is understood that eachintervening value, to the smallest fraction of the unit of the lowerlimit, unless the context clearly dictates otherwise, between the upperand lower limits of that range is also specifically disclosed. Anynarrower range between any stated values or unstated intervening valuesin a stated range and any other stated or intervening value in thatstated range is encompassed. The upper and lower limits of those smallerranges may independently be included or excluded in the range, and eachrange where either, neither, or both limits are included in the smallerranges is also encompassed within the technology, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural references unless the context clearly dictatesotherwise. Thus, for example, reference to “a precursor” includes aplurality of such precursors, and reference to “the layer” includesreference to one or more layers and equivalents thereof known to thoseskilled in the art, and so forth.

Also, the words “comprise(s)”, “comprising”, “contain(s)”, “containing”,“include(s)”, and “including”, when used in this specification and inthe following claims, are intended to specify the presence of statedfeatures, integers, components, or operations, but they do not precludethe presence or addition of one or more other features, integers,components, operations, acts, or groups.

The invention claimed is:
 1. An etching method comprising: flowing ahydrogen-containing precursor into a semiconductor processing chamber;flowing a fluorine-containing precursor into a remote plasma region ofthe semiconductor processing chamber; forming a plasma of thefluorine-containing precursor in the remote plasma region; etching apre-determined amount of a silicon-containing material from a substratein a processing region of the semiconductor processing chamber;measuring a radical density within the remote plasma region during theetching; and halting the flow of the hydrogen-containing precursor intothe semiconductor processing chamber when the radical density measuredover time correlates to a produced amount of etchant to remove thepre-determined amount of the silicon-containing material.
 2. The etchingmethod of claim 1, wherein the measuring is of an atomic trace ofhydrogen within the remote plasma region of the semiconductor processingchamber.
 3. The etching method of claim 2, wherein thehydrogen-containing precursor comprises hydrogen, ammonia, or water. 4.The etching method of claim 2, wherein the measuring is performed withan optical emission spectrometer positioned within a dielectriccomponent at least partially defining the remote plasma region of thesemiconductor processing chamber.
 5. The etching method of claim 4,wherein the measuring comprises measuring a peak intensity of radicalhydrogen within the remote plasma region of the semiconductor processingchamber.
 6. The etching method of claim 2, further comprising, prior tohalting the flow of the hydrogen-containing precursor, identifying anincrease in the atomic trace within the remote plasma region.
 7. Theetching method of claim 6, wherein the increase correlates to completeremoval of the silicon-containing material.
 8. The etching method ofclaim 1, wherein the remote plasma region is a region defined within thesemiconductor processing chamber and separated from the processingregion by one or more chamber components.
 9. The etching method of claim1, further comprising flowing an inert precursor into the remote plasmaregion and forming a plasma of the inert precursor within the remoteplasma region.
 10. The etching method claim 9, wherein a stable plasmaof the inert precursor is produced prior to flowing thefluorine-containing precursor into the remote plasma region.
 11. Theetching method of claim 1, wherein the hydrogen-containing precursor isflowed to bypass the remote plasma region during the etching method. 12.An etching method comprising: flowing a hydrogen-containing precursorinto a semiconductor processing chamber; flowing a fluorine-containingprecursor into a remote plasma region of the semiconductor processingchamber; forming a plasma of the fluorine-containing precursor in theremote plasma region; etching in a first etch process a pre-determinedamount of a silicon-containing material from a substrate in a processingregion of the semiconductor processing chamber; measuring a radicaldensity within the remote plasma region during the etching; halting theflow of the hydrogen-containing precursor into the semiconductorprocessing chamber when the radical density measured over timecorrelates to a produced amount of etchant to remove the pre-determinedamount of the silicon-containing material; removing the substrate fromthe semiconductor processing chamber; forming a plasma of afluorine-containing precursor in the semiconductor processing chamber;measuring a radical density of the hydrogen-containing precursor;extinguishing the plasma of the fluorine-containing precursor when theradical density of the hydrogen-containing precursor reaches apre-determined threshold; and performing a second etch process.
 13. Theetching method of claim 12, wherein the first etch process and thesecond etch process are different etch processes.
 14. The etching methodof claim 12, wherein the first etch process comprises a first etch for adual damascene etch process, and wherein the second etch processcomprises a second etch for a dual damascene etch process.